An IEEE 802.16 wireless local area network (LAN) based high-speed portable Internet (HPi) is a 3.5 generation mobile communication system that provides image data and high-speed packet data transmission of various Internet protocol (IP) based wireless data services (e.g., streaming video, FTP, e-mail, chatting, etc.) available in a wired Internet using a wireless transmission technology that guarantees spectrum use efficiency in a frequency band of 2.3 GHz.
In general, a portable Internet system includes an access terminal (AT), an access point (AP) that supports a wireless access and a network connection of the AT, and a packet access router (PAR) performing mobility control and packet routing of each AT. The AP performs access control of the AT, packet matching between wired and wireless networks, wireless transmitting/receiving control, and radio resource management, and more particularly, it performs traffic processing and packet scheduling, wireless link control, radio resource management, and hybrid automatic repeat request (HARQ) control.
The portable Internet system transmits/receives data by frames to support high-speed packet data transmission in a wireless network, and employs orthogonal frequency division multiplexing (OFDM)/frequency division multiplexing access (FDMA)/time division duplex (TDD) wireless transmission algorithms. According to the OFDM/FDMA/TDD wireless transmission algorithms, data is transmitted and received on a subchannel formed of a subcarrier group and every frame transmits a MAP message at the beginning of each frame, and a data burst is transmitted subsequent to transmission of the MAP message. The MAP message contains frame configuration information.
Therefore, a scheduler allocates a subchannel for user data transmission of every frame, performs management scheduling, and composes a MAP message based on information on the scheduling. In general, system efficiency and transmission characteristics are greatly dependent on a scheduling algorithm employed by the AP, and implementation of the scheduling algorithm may vary according to the desired purpose.
The scheduling algorithm is implemented as a method for maximizing transmission efficiency of the system and guaranteeing fairness between terminals.
The maximization of transmission efficiency of the system is achieved by allocating a large amount of radio resource to a terminal having good channel quality. However, a terminal having bad channel quality cannot be provided with the radio resource even though the terminal has a large amount of data to transmit, and accordingly, the terminal may not be provided with the desired services.
A method for guaranteeing fairness between terminals is to allocate the radio resource evenly to every terminal without regard to channel quality. However, this method may reduce system efficiency because a great amount of radio resource may be allocated to the terminal having bad channel quality.
The portable Internet system provides various types of multimedia services such as a real-time service, a non real-time service, a best effort service, etc., but a conventional portable Internet system employs a scheduling algorithm appropriate for only a simple service rather than employing a scheduling algorithm that satisfies various conditions required for each service characteristic.
In addition, a minimum processing time should be guaranteed for scheduling of a conventional portable Internet system because the scheduling should be performed accurately corresponding to frame synchronization and a MAP message should be generated in advance while the scheduling is performed. Accordingly, a scheduling load may occur and affect the frame synchronization.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.